69 lines
1.2 KiB
Bash
Executable File
69 lines
1.2 KiB
Bash
Executable File
#!/usr/bin/env bash
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bin() {
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local str num=$1
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while (( num > 0 )); do
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str=$(( num % 2 ))$str
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(( num /= 2 ))
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done
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while (( ${#str} < 8 )); do
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str=0$str
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done
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printf %s "$str"
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}
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dec() {
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local pow=$(( ${#1} - 1 )) num=0
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for (( count = 0; count < ${#1}; ++count )); do
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(( num += ${1:count:1} * (2 ** pow) ))
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(( pow -= 1 ))
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done
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printf %d "$num"
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}
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2ip() {
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local ip=( ) count
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for count in {0..3}; do
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ip[$count]=$(dec "${1:count * 8:8}")
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done
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printf %s.%s.%s.%s "${ip[@]}"
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}
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if (( ! $# )); then
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printf 'usage: %s ip/cidr\n' "$0"
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exit 1
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fi
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IFS=/ read -r ip size <<< "$1"
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IFS=. read -ra octets <<< "$ip"
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for (( count = 0; count < 4; ++count )); do
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octets[$count]=$(bin "${octets[$count]}")
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done
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IFS= ip=${octets[*]} network=${ip:0:size} broadcast=${ip:0:size}
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while (( ${#network} < 32 )); do
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network+=0
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broadcast+=1
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done
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for (( count=0; count < size; ++count )); do
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mask+=1
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done
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for (( count=32 - size; count < 32; ++count )); do
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mask+=0
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done
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printf 'subnet mask: %s\n' "$(2ip "$mask")"
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printf 'range: %s - %s\n' "$(2ip "$network")" "$(2ip "$broadcast")"
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printf 'total assignable hosts: %d\n' "$(( (2 ** (32 - size)) - 2 ))"
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